fix collisions between projectiles and players

[vinport16]

right now, the center of the projectile needs to pass through the player cylinder. I want to have loadouts with different projectile sizes, and have that actually change the behavior of the projectile.

we may need to approximate the player hitbox into a capsule: https://stackoverflow.com/questions/15310239/collision-detection-response-between-a-moving-sphere-and-a-circular-cylinder

it would be nice to make the hitbox a true cylinder though..

[vinport16]

didn't need to approximate to a capsule. fixed in 85079abb9b10772fb8ccfdab88a7359a28165a0f